Measuring the energy absorbing capacity of a substrate

ABSTRACT

Apparatus for measuring the energy absorption capacity of a substrate, comprises: a probe ( 1 ); means for driving the probe ( 1 ) into the substrate so that the probe ( 1 ) penetrates the substrate; measuring means ( 4, 8 ) arranged to take a plurality of measurements of the force applied to the probe ( 1 ) and of the displacement of the probe ( 1 ) as the probe ( 1 ) penetrates the substrate; and processing means ( 12 ) arranged to integrate instantaneous readings of both said measurements to give a measurement of the energy required to drive the probe ( 1 ) into the substrate and hence determine a measurement of the energy absorbing capacity of the substrate. A corresponding method is also disclosed.

This application claims priority to PCT/GB99/03098, filed Sep. 17, 1999,which published on Mar. 30, 2000 with Publication No. WO 00/17622 in theEnglish language and which claimed priority to GB Patent Application No.9820616.2, filed Sep. 23, 1998.

FIELD OF INVENTION

This invention relates to apparatus for, and a method of, measuring theenergy absorbing capacity of the surface of a racecourse and,particularly, the application of this to providing a measurement of the“going” of such a racecourse.

BACKGROUND TO THE INVENTION

A large proportion of horse-racing takes place on turf courses.

The “going” of a course varies depending on, among other things, how ithas been managed and how wet it is. It is well-known that race timesvary depending on the state of the course and that hard ground brings anincreased risk of injury to horse and rider. During the run up to racemeetings, and at the events themselves, the state of the course is ofinterest to the racing authorities, trainers, owners, jockeys andpunters.

The “going” of a racecourse is traditionally measured by a personpressing a walking stick into the ground and that person making anassessment of the “going”, e.g. as “soft”, “firm” or “hard” and in somecases seven levels of assessment are given). This assessment is,however, highly subjective, especially on firm ground, and even thoughsuch assessments are carried out only by a small number of highlyexperienced people, it is common for their assessments to vary.Moreover, in many cases, the “going” will be different on differentparts of the racecourse.

BE-A-876648 discloses an apparatus for measuring the mechanicalcharacteristics of a body. The apparatus described comprises purelymechanical components and has the disadvantage that it is difficult forit to be used by unskilled operators on racetracks to give repeatable,accurate indications of the prevailing “going” conditions.

GB-A-942614 describes an instrument for the indication of the “going” ofracecourses and the like, but this instrument is merely capable ofmeasuring only compressive forces exerted on the racecourse surface anddoes not allow the user to determine the energy absorption capacity ofthe surface. Thus, the device disclosed has the disadvantage thataccurate measurement of the “going” of racecourses (which more property,requires measurement based upon energy absorption capacity) is notpossible.

Further, various other attempts have been made to provide a quantitativemeasurement of the “going” of a racecourse but the applicants areunaware of any successful and reliable solution to this problem.

Hence, the present invention aims to provide apparatus and a method forproviding a quantitative measurement of the energy absorbing capacity ofthe surface of a racecourse and thus, in particular, accurate andrespectable assessment of the “going” of such a racecourse.

SUMMARY OF THE INVENTION

Thus, according to a first aspect of the invention, there is providedapparatus for providing quantitative assessment of the “going” of aracecourse by measuring the mechanical energy absorption capacity of theracecourse surface, comprising: a probe; drive means for automaticallydriving the probe into the surface so that the probe penetrates thesurface; measuring means arranged to take a plurality of measurements ofthe force applied to the probe and of the displacement of the probe asthe probe automatically penetrates the surface; and processing meansarranged to integrate instantaneous readings of both said measurementsto give a measurement of the mechanical energy required to drive theprobe into the surface and hence provide a measurement of the mechanicalenergy absorbing capacity of the racecourse surface, so as to provide aquantitative assessment of the “going” of the racecourse.

According to a second aspect of the invention, there is provided amethod of providing quantitative assessment of the “going” of aracecourse by measuring the mechanical energy absorbing capacity of theracecourse surface comprising the steps of: automatically driving aprobe into the surface so the probe penetrates the substrate, taking aplurality of measurements of the force applied to the probe and thedisplacement of the probe as it penetrates the substrate, andintegrating instantaneous readings of both said measurements to providea measurement of the mechanical energy required to drive the probe intothe surface and hence provide a measurement of the mechanical energyabsorbing capacity of the substrate, so as to provide a quantitativeassessment of the “going” of the racecourse.

The invention also relates to the use of the above described apparatusor method to provide a quantitative assessment of the “going” of aracecourse by measurement of the mechanical energy absorbing capacity ofthe surface of the racecourse.

Other features of the invention will be apparent from the followingdescription and from the subsidiary claims of the specification.

The invention will now be further described, merely by way of example,with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a preferred embodiment of apparatus accordingto the invention;

FIGS. 2 and 3 are enlarged, front and bottom views of a preferred formof probe used in the apparatus; and

FIG. 4 is a flow diagram of a preferred procedure for carrying outmeasurements using the apparatus.

BEST MODE OF INVENTION

The invention will hereinafter be described in relation to its use inproviding a measurement of the “going” of a racecourse, the surface ofwhich comprises turf, which is a very non-homogeneous material, althoughthe invention can also be applied to other types of surface, e.g. bareearth, sand, snow or a synthetic surface (e.g. comprising a mixture ofsand and organic or synthetic fibres). However, it will be appreciatedthat the invention may also be used for measuring the energy absorbingcapacity of other sports surfaces, substrates carrying any form oftraffic (human, animal or mechanical) or substrates used for any otherpurpose. The term “racecourse” as used herein includes courses used fortraining.

A first important feature of the present invention is the use of ameasurement of the energy absorbing capacity of a racecourse to providean assessment of the “going” of the racecourse. As the “going” has,until now, been a subjective assessment, it was first necessary toselect a measurement which was capable of reflecting this assessment. Awide variety of parameters could be measured, e.g. the hardness of theground, its compaction, its stiffness or resilience, its composition,its water content etc, but the measurement of the energy absorbingcapacity was selected as this was considered to most closely reflect thework done by a horse's hoof as it moves over the racecourse, andexperimental trials have shown that the results provide a good match tothe current subjective assessment of the “going” of a racecourse.

The energy absorbing capacity of the substrate may be defined as theenergy required to drive the probe into the ground and/or the energyrequired to subsequently extract the probe from the ground.

The apparatus shown in FIG. 1 comprises a probe 1 in the form of asubstantially conical spike with substantially flat wings 2 attached onopposite sides thereof.

The probe 1 is secured to a mounting 2. The mounting 2 is secured tosteel guide rails 2A which are slidably mounted within a guide unit 7.The guide unit 7 is rigidly mounted to four steel support rails 3 whichare preferably provided at the corners of a square (when the apparatusis viewed from above) although other arrangements would be possible. Themounting of the guide rails 2A within guide unit 7 ensures that theprobe can only move axially and cannot be displaced at an angle to theaxis thereof. The mounting 2 is also attached by a shaft 2B to drivemeans in the form of a pneumatic cylinder 5 so that movement of a piston(not shown) within the pneumatic cylinder 5 causes the probe 1 to bemoved axially, i.e. up and down in the orientation shown in FIG. 1. Theprobe 1 can thus be moved so it passes through an aperture in a steelbase plate 6 and can be retracted again to the position shown in FIG. 1.

A force transducer 4 is mounted in the connection between the shaft 2Band the pneumatic cylinder to measure the force applied to the probe 1.

A position transducer 8 in the form of a rotary potentiometer is mountedon the apparatus and, in the arrangement shown, measures the axialdisplacement of the probe 1 by means of a pulley 9, band 10 and linkagerod 13. The linkage rod 13 is rigidly attached to the shaft 2B and tothe band 10 so that linear motion of the probe 1 is converted intorotary motion of the potentiometer.

Other types of force and position transducers may be used.

The pneumatic cylinder 5 is controlled by a pneumatic control valve 11,which, in turn, is controlled by an electronic control unit 12.

As shown in FIGS. 2 and 3, the probe 1 preferably has a generallyconical shape with substantially flat wings 1B on opposite sidesthereof. The probe may, for example, comprise a solid steel cone 1A withwings 1B welded to the sides thereof or, as shown in FIG. 3, the wings1B may comprise a single sheet of steel with two halves 1D and 1E of acone attached on opposite sides thereof. The wings 1B are substantiallyco-planar with the axis of the cone. More than two such wings may beprovided if required.

In use, the apparatus is positioned with the base plate 6 held in firmcontact with the ground. The drive means is then activated so the probe1 is driven into and penetrates the ground. When the probe 1 stopsmoving, the drive means is reversed to extract the probe 1 from theground until it is retracted above to a position above the base plate 6,as shown in FIG. 1. The extent to which the probe penetrates the groundwill be determined by the maximum force permitted by the air pressureapplied to the pneumatic cylinder and the hardness of the ground.

Whilst the probe 1 is being driven into the ground, and preferably alsowhilst it is being extracted from the ground, readings are taken eithercontinuously or at frequent intervals from the force transducer 4 andthe position transducer 8 by the electronic control unit. In a preferredarrangement readings are taken at the rate of at least 100 samples persecond and preferably at least 500 samples per second. In a preferredarrangement, the time taken to drive the probe into the ground is lessthan one second.

It will be appreciated that by integrating the instantaneous readingsfrom the force transducer 4 and position transducer 8 during the timethe probe is penetrating the ground and, again, whilst it is beingextracted from the ground, the apparatus is able to measure the energyrequired to drive the probe into the ground (and, optionally, to extractit again) and thus obtain a measurement of the energy absorbed by theground during the measurement cycle. Further details of methods ofprocessing the readings taken will be given below.

The apparatus may, optionally, also be provided with an accelerometer 14to measure the acceleration and/or deceleration of the probe 1. Theaccelerometer may be mounted on the shaft 2A and readings takentherefrom at similar intervals to the readings from the force transducer4 and position transducer 8.

The accelerometer is preferably used to determine the maximumdeceleration of the probe 1 as it penetrates the ground as it is foundthat, on some surfaces, e.g. synthetic surfaces comprising a compactionof loose material, this measurement can be used to help differentiatebetween “firm” and “hard” surfaces. It may also be used to provide ameasurement of the hardness (or stiffness) of a surface which can beused to assess whether the surface is safe to use.

The maximum deceleration can be determined by scanning the readings fromthe accelerometer during the penetration phase of a measurement cycle tolocate the maximum reading, or a high speed sample and hold circuit(e.g. 10 KHz) can be used to capture the maximum deceleration.

If an accelerometer is used, the apparatus is preferably arranged sothat the tip of the probe is at least 20 mm away from the ground beforea measurement cycle is initiated so that the probe has time toaccelerate before it engages the ground. The apparatus is thus arrangedso that the probe can be retracted to a position at least 20 mm abovethe base plate 9.

The shape of the probe 1 is designed so that it is sufficiently sharp topenetrate the ground, e.g. to penetrate through thick turf, and it has aconical or tapered shape so that the sides of the probe continue todeform the ground as the probe penetrates the ground. This ensures thatuseful readings can continue to be taken throughout the vertical extentof the travel of the probe as it penetrates the ground.

The wings 1B provide additional resistance as the probe penetrates theground and, because they are substantially flat, their sides also remainin contact with ground as the probe is withdrawn so that useful readingscan be taken whilst the probe is being extracted from the ground.

In a preferred example of the apparatus, the probe has a length of about150 mm (from the tip of the case to the base thereof) and the base ofthe cone has a width of about 60 mm and it has been found that themaximum force required to drive such a probe into dense ground is about600 N.

The shape of the probe should also be such that it provides usefulmeasurements in a range of different types of ground and over the rangeof “goings” likely to be encountered.

As mentioned above, the probe is preferably driven through a circularaperture in the base plate 6. The circular aperture preferably has adiameter slightly larger than the combined width of the base of the coneand the wings at the base of the cone, e.g. of about 80 mm. The baseplate 6 is in contact with the ground as the probe penetrates the groundand it serves to restrain material displaced by the probe and limits theextent to which this displaced material can rise above ground level.This helps ensure that the ground is deformed in a uniform, controlledmanner by the probe 1 so the apparatus provides more consistent andreliable measurements. This arrangement is also beneficial in preventingclods of soil adhering to the probe 1 so reducing the need to clean theprobe between measurements.

The force transducer 4 is preferably an electronic analogue forcetransducer which is arranged to measure both pulling and pushing forcesand it is arranged so that it is only subject to axial forces and is notsubject to any lateral thrusts.

The electronic control unit 12 is preferably arranged to scan operationof a start switch (not shown) and controls the air supply to thepneumatic cylinder 5. When measurements have been taken, the controlunit 12 makes a stepwise integration of the force and position data forpenetration and extraction of the probe 1. The upward velocity of theprobe is measured at the point when the tip of the probe is passing theground surface. This velocity is used to compute the kinetic energywhich is subtracted from the extraction energy integral to leave onlythat which is due to the ground condition. These results, together withdata on the penetration distance, the penetration and/or extractiontime, maximum force and, optionally, the acceleration/deceleration ofthe probe, are used for further processing, storage and display eitherby the control unit 12 or by other means connected thereto, e.g. apersonal computer (not shown).

The control unit runs a background task that takes the analoguemeasurements and stores them in a ring buffer. The foregound taskmanages the start switch, monitors the ring buffer results for the endof penetration and the end of measurement and drives the pneumaticcontrol valves. It also integrates the force and position data andtransmits each test result to the attached computer.

The computer receives each test result, scales the measurements intoengineering units and updates a user display. The data for each testresult is saved in a file.

Once a set of test data has been scaled and its validity checked, it isused to compute a numerical “going” rating. A number of “going” rating sare combined and presented as a measured “going”.

Tests with the apparatus have been compared with subjective testscarried out in the manner described above and calibrated in relationthereto. The test results have provided consistent, repeatable readings,which are well-matched to the results of the subjective assessments.

As indicated above, it is found that, in some circumstances, acombination of a measurement of the energy absorption with a measurementof the maximum deceleration of the probe enables the “going”,particularly a “firm” to “hard” “going” to be assessed more reliably.Tests have shown that the maximum deceleration on “hard” ground may bearound 25 to 30 g, on “good” ground it may be around 2 to 3 g, and on“soft” ground it would be very small, e.g. less than 1 g.

FIG. 4 shows a flow chart describing the function of the control unit12. With the description given above, this flow chart isself-explanatory so will not be described further.

The apparatus described above enables a quantitative measurement of the“going” of a racecourse, which is more repeatable and more reliable thanthe current subjective assessment. It also enables a finer assessment ofthe “going” and may, for example, give “going” ratings from 15 (for“heavy”) to 85 (for “hard”). Ratings of 15 to 85 may, for example, begiven as an assessment of the “going” corresponding to the conventionalassessments as follows:

15 to 25 represent a “heavy” going;

25 to 35 represent a “soft” going;

35 to 45 represent a “good to soft” going;

45 to 55 represent a “good” going;

55 to 65 represent a “good to firm” going;

65 to 75 represent a “firm” going; and

75 to 85 represent a “hard” going.

More accurate measurements can be given by numbers within the aboveranges, e.g. to indicate that the “going” is towards the hard or softend of a given rating. This system is thus capable of providing 70levels of assessment (i.e. the numbers from 15 through 85) ranging fromthe softest to the hardest “going”. Other ranges and forms ofcalibration may, of course, be used in place of that described above.

What is claimed is:
 1. Apparatus for providing a quantitative assessmentof the “going” of a racecourse by measuring the mechanical energyabsorption capacity of the racecourse surface, comprising: a probe (1);means for automatically driving the probe (1) into the surface of theracecourse o that the probe (1) penetrates the surface; measuring means(4,8) arranged to take a plurality of measurements of the force appliedto the probe (1) and of the displacement of the probe (1) as the probe(1) automatically penetrates the surface; and processing means (12)arranged to integrate instantaneous readings of both said measurementsto give a measurement of the mechanical energy required to drive theprobe (1) into the surface and hence determine a measurement of themechanical energy absorbing capacity of the racecourse surface, so as toprovide a quantitative assessment of the “going” of the racecourse. 2.The apparatus of claim 1, wherein the probe has a substantially conicalshape, arranged such that, in use, the narrow end thereof is directedtowards the surface.
 3. The apparatus of claim 2, wherein thesubstantially conical probe has at least two substantially planar wingsarranged to be co-planar with the axis of the conical probe.
 4. Theapparatus of claim 1, comprising a plate which is adapted to be holdablein contact with the surface to be tested, the probe being arranged topass through an aperture in the plate as it is driven into the surface.5. The apparatus of claim 1, wherein the drive means comprises apneumatic cylinder.
 6. The apparatus of claim 1, wherein the measuringmeans comprises a force transducer for measuring the force applied tothe probe and a position transducer for measuring the displacement ofthe probe as it is driven into the surface.
 7. The apparatus of claim 1,wherein the measuring means is also adapted to measure the force appliedto the probe and the displacement of the probe during extraction of theprobe from the surface.
 8. The apparatus of claim 1, wherein saidmeasurements are measurable as the probe penetrates the surface untilthe probe stops or until the application of a predetermined level offorce to the probe.
 9. The apparatus of claim 1, wherein saidmeasurements are continuously measurable during movement of the probe ormeasurable at frequent intervals, the frequent intervals being one of atleast 100 measurements per second and at least 500 measurements persecond, during such movement.
 10. The apparatus of claim 1, wherein theprocessing means is arranged to integrate the said measurements toprovide a measure of the energy absorbing capacity of the surface. 11.The apparatus of claim 1, wherein the measuring means is arranged tomeasure one or more of: the distance the probe penetrates the surface,the time taken for the probe to penetrate the surface and/or beextracted therefrom and the maximum force applied to the probe by thedriving means.
 12. The apparatus of claim 1, wherein the quantitativeassessment of the “going” is providable as one of a range of at least 7,and preferably at least 70, levels of assessment ranging from thesoftest “going” to the hardest “going”.
 13. The apparatus of claim 1,comprising an accelerometer for measuring the acceleration/decelerationof the probe.
 14. The apparatus of claim 13, wherein measurements fromthe accelerometer are used to determine the maximum deceleration of theprobe as it penetrates the surface.
 15. The apparatus of claim 14,wherein the measurements of the energy absorbing capacity of the surfaceand of the maximum deceleration of the probe are combinable to providethe quantitative assessment of the “going” of the racecourse.
 16. Amethod for providing a quantitative assessment of the “going” of aracecourse by measuring the mechanical energy absorbing capacity of theracecourse surface comprising: automatically driving a probe into thesurface so the probe penetrates the surface, taking a plurality ofmeasurements of the force applied to the probe and the displacement ofthe probe as it penetrates the substrate, and integrating instantaneousreadings of both said measurements to provide a measurement of themechanical energy required to drive the probe into the surface and henceprovide a measurement of the mechanical energy absorbing capacity of theracecourse surface so as to provide a quantitative assessment of the“going” of the racecourse.
 17. The apparatus of claim 16, wherein themeasurement of the acceleration/deceleration of the probe are taken andcombined with the measurement of the energy absorbing capacity of thesurface to provide the quantitative assessment of the “going” of theracecourse.
 18. The apparatus of claim 17, wherein the surface of theracecourse comprises turf.